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Expect - bad command trap

Posted by sgy258 (sgy258), 13 January 2004
I have an existing expect program that is used to spawn a telnet session and automatically login a user to a server. I would like to trap certain commands to prevent users from executing those commands (passwd, etc.). I modified my program according to Don Libes "Exploring Expect" Preventing - Bad Commands example on page 347.

The command trap works, however when a user types a string, the string is echoed back on the next line - example:

guest@gumby> pwd

Is there a way to prevent the string from echoing a new line with the command?

Here is the section of code:

set prompt ">"
set badcmds "passwd|su"

interact {
-o -reset -nobuffer -re $prompt {
while 1 {
set timeout 1800
expect_user {
-re "^badcmds.*"
send_user "Command not allowed...!\n"
sleep 3
-re "(.*)\n"
send "$expect_out(1,string)\r"
timeout {

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